db3a3d8fc0
On modern operating systems, memory management is non-deterministic (i.e. random, unpredictable) to varying degrees. This makes testing for memory leaks a nightmare as the OS may decide to randomly grow a process's memory allocation at any time for no apparent reason, causing intermittent test failures that do not represent real memory leaks. So far, the leaks test tried to cope with this by using a large number of iterations plus a certain amount of bytes of tolerance per iteration. This was inefficient and on some systems still did not fully eliminate intermittent test failures. This commit introduces a new testing algorithm that is designed to cope with a large degree of unpredictability. Instead of a fixed number of test iterations, it defines a maximum (16384), dividing them in blocks of 128 iterations. It also defines a minimum number of sequential "good" iteration blocks, counted if memory usage did not increase from one block to the next. That minimum number is set to 16. The theory is that if we can get 16 "good" iteration blocks in a row, we can safely assume it's not a real memory leak, break the loop, and consider the test succeeded. That "good" sequence is allowed to occur at any point in the loop, creating a high built-in tolerance for non-deterministic shenanigans. It also speeds up the tests, as successful tests can bow out at 16 * 128 == 2048 iterations if they're lucky. If the OS decides to randomly grow the memory heap, it may take more tries, but almost (?) certainly not more than the maximum 16384 (128 blocks). If the counter reaches that, then we assume a memory leak and throw a test failure. We're also no longer testing with byte granularity in any case; the randomness of memory management makes that pointless. All getmem() function versions now return kibibytes (1024 bytes). This should eliminate the need for workarounds such as initial iterations to "steady the state" or a tolerance of a certain number of bytes. I've experimentally determined the exact values (max_iter, block_iter, min_good_blocks) that seem to work reliably on all systems I've tested. They are easy to tweak if necessary. To make all this manageable, this commit hides all the supporting code in a triplet of aliases (TEST, DO, DONE) that, when used correctly, create a grammatically robust shell code block: you can add redirections, pipe into it, etc. as expected. This makes the actual tests a great deal easier to read as well. src/cmd/ksh93/tests/pty.sh: - Implement new leaks testing framework as described and convert all the tests to it. - Mark known leaks with a 'known' variable. Print non-fail warnings for all known leaks, but skip the tests by default. Test them only if DEBUG is exported. This is better than commenting them out as we will no longer be tempted to forget about these. - Move the test for large command substitutions to subshell.sh -- it's not in fact a leak test; instead, it checks that command substitutions don't lose data. src/cmd/ksh93/tests/_common: err_exit(): - Since we're printing more warnings, clearly mark all test failures with 'FAIL:' to make them stand out. src/cmd/ksh93/tests/shtests. src/cmd/ksh93/tests/pty.sh: - Special-case leaks.sh for counting tests; grep ^TEST. - Special-case pty.sh as well while we're at it by grepping tst() calls. Remove all the dummy '# err_exit #' comments from pty.sh as they are now no longer used for counting the tests. |
||
|---|---|---|
| .github/workflows | ||
| bin | ||
| docs | ||
| src | ||
| .gitignore | ||
| ANNOUNCE | ||
| COPYRIGHT | ||
| LICENSE.md | ||
| NEWS | ||
| README.md | ||
| TODO | ||
KornShell 93u+m
This repository is used to develop bugfixes to the last stable release (93u+ 2012-08-01) of ksh93, formerly developed by AT&T Software Technology (AST). The sources in this repository were forked from the GitHub AST repository which is no longer under active development.
For user-visible fixes, see NEWS and click on commit messages for full details. For all fixes, see the commit log. To see what's left to fix, see the issue tracker.
Policy
- Fixing bugs is main focus of the 1.x series. Major feature development is for future versions (2.x and up).
- No major rewrites. No refactoring code that is not fully understood.
- No changes in documented behaviour, except if required for compliance with the POSIX shell language standard which David Korn intended for ksh to follow.
- No 100% bug compatibility. Broken and undocumented behaviour gets fixed.
- No bureaucracy, no formalities. Just fix it, or report it: create issues, send pull requests. Every interested party is invited to contribute.
- To help increase everyone's understanding of this code base, fixes and significant changes should be fully documented in commit messages.
- Code style varies somewhat in this historic code base.
Your changes should match the style of the code surrounding them.
Indent with tabs, assuming an 8-space tab width.
Opening braces are on a line of their own, at the same indentation level
as their corresponding closing brace.
Comments always use
/*...*/. - Good judgment may override this policy.
Why?
Between 2017 and 2020 there was an ultimately unsuccessful attempt to breathe new life into the KornShell by extensively refactoring the last unstable AST beta version (93v-). While that ksh2020 branch is now abandoned and still has many critical bugs, it also had a lot of bugs fixed. More importantly, the AST issue tracker now contains a lot of documentation on how to fix those bugs, which made it possible to backport many of them to the last stable release instead. This ksh 93u+m reboot now incorporates many of these bugfixes, plus patches from OpenSUSE, Red Hat, and Solaris, as well as many new fixes from the community (1, 2). Though there are many bugs left to fix, we are confident at this point that 93u+m is already the least buggy branch of ksh93 ever released.
Build
To build ksh with a custom configuration of features, edit
src/cmd/ksh93/SHOPT.sh.
Then cd to the top directory and run:
bin/package make
The compiled binaries are stored in the arch directory, in a subdirectory
that corresponds to your architecture. The command bin/package host type
outputs the name of this subdirectory.
If you have trouble or want to tune the binaries, you may pass additional
compiler and linker flags. It is usually best to export these as environment
variables before running bin/package as they could change the name of
the build subdirectory of the arch directory, so exporting them is a
convenient way to keep them consistent between build and test commands.
Note that this system uses CCFLAGS instead of the usual CFLAGS.
An example that makes Solaris Studio cc produce a 64-bit binary:
export CCFLAGS="-m64 -O" LDFLAGS="-m64"
bin/package make
Alternatively you can append these to the command, and they will only be used for that command. You can also specify an alternative shell in which to run the build scripts this way. For example:
bin/package make SHELL=/bin/bash CCFLAGS="-O2 -I/opt/local/include" LDFLAGS="-L/opt/local/lib"
For more information run
bin/package help
Many other commands in this repo self-document via the --help, --man and
--html options; those that do have no separate manual page.
Test
After compiling, you can run the regression tests. Start by reading the information printed by:
bin/shtests --man
Install
Automated installation is not supported yet. To install manually:
cp arch/$(bin/package host type)/bin/ksh /usr/local/bin/
cp src/cmd/ksh93/sh.1 /usr/local/share/man/man1/ksh.1
(adapting the destination directories as required).
What is ksh93?
The following is the official AT&T description from 1993 that came with the ast-open distribution. The text is original, but hyperlinks were added here.
KSH-93 is the most recent version of the KornShell Language described in "The KornShell Command and Programming Language," by Morris Bolsky and David Korn of AT&T Bell Laboratories, ISBN 0-13-182700-6. The KornShell is a shell programming language, which is upward compatible with "sh" (the Bourne Shell), and is intended to conform to the IEEE P1003.2/ISO 9945.2 Shell and Utilities standard. KSH-93 provides an enhanced programming environment in addition to the major command-entry features of the BSD shell "csh". With KSH-93, medium-sized programming tasks can be performed at shell-level without a significant loss in performance. In addition, "sh" scripts can be run on KSH-93 without modification.
The code should conform to the IEEE POSIX 1003.1 standard and to the proposed ANSI C standard so that it should be portable to all such systems. Like the previous version, KSH-88, it is designed to accept eight bit character sets transparently, thereby making it internationally compatible. It can support multi-byte characters sets with some characteristics of the character set given at run time.
KSH-93 provides the following features, many of which were also inherent in KSH-88:
- Enhanced Command Re-entry Capability: The KSH-93 history function records commands entered at any shell level and stores them, up to a user-specified limit, even after you log off. This allows you to re-enter long commands with a few keystrokes - even those commands you entered yesterday. The history file allows for eight bit characters in commands and supports essentially unlimited size histories.
- In-line Editing: In "sh", the only way to fix mistyped commands is to backspace or retype the line. KSH-93 allows you to edit a command line using a choice of EMACS-TC or "vi" functions. You can use the in-line editors to complete filenames as you type them. You may also use this editing feature when entering command lines from your history file. A user can capture keystrokes and rebind keys to customize the editing interface.
- Extended I/O Capabilities: KSH-93 provides several I/O capabilities not
available in "sh", including the ability to:
- specify a file descriptor for input and output
- start up and run co-processes
- produce a prompt at the terminal before a read
- easily format and interpret responses to a menu
- echo lines exactly as output without escape processing
- format output using printf formats.
- read and echo lines ending in "\".
- Improved performance: KSH-93 executes many scripts faster than the System V Bourne shell. A major reason for this is that many of the standard utilities are built-in. To reduce the time to initiate a command, KSH-93 allows commands to be added as built-ins at run time on systems that support dynamic loading such as System V Release 4.
- Arithmetic: KSH-93 allows you to do integer arithmetic in any base from two to sixty-four. You can also do double precision floating point arithmetic. Almost the complete set of C language operators are available with the same syntax and precedence. Arithmetic expressions can be used to as an argument expansion or as a separate command. In addition, there is an arithmetic for command that works like the for statement in C.
- Arrays: KSH-93 supports both indexed and associative arrays. The subscript for an indexed array is an arithmetic expression, whereas, the subscript for an associative array is a string.
- Shell Functions and Aliases: Two mechanisms - functions and aliases - can be used to assign a user-selected identifier to an existing command or shell script. Functions allow local variables and provide scoping for exception handling. Functions can be searched for and loaded on first reference the way scripts are.
- Substring Capabilities: KSH-93 allows you to create a substring of any given string either by specifying the starting offset and length, or by stripping off leading or trailing substrings during parameter substitution. You can also specify attributes, such as upper and lower case, field width, and justification to shell variables.
- More pattern matching capabilities: KSH-93 allows you to specify extended regular expressions for file and string matches.
- KSH-93 uses a hierarchical name space for variables. Compound variables can be defined and variables can be passed by reference. In addition, each variable can have one or more disciplines associated with it to intercept assignments and references.
- Improved debugging: KSH-93 can generate line numbers on execution traces. Also, I/O redirections are now traced. There is a DEBUG trap that gets evaluated before each command so that errors can be localized.
- Job Control: On systems that support job control, including System V Release 4, KSH-93 provides a job-control mechanism almost identical to that of the BSD "csh", version 4.1. This feature allows you to stop and restart programs, and to move programs between the foreground and the background.
- Added security: KSH-93 can execute scripts which do not have read permission and scripts which have the setuid and/or setgid set when invoked by name, rather than as an argument to the shell. It is possible to log or control the execution of setuid and/or setgid scripts. The noclobber option prevents you from accidentally erasing a file by redirecting to an existing file.
- KSH-93 can be extended by adding built-in commands at run time. In addition, KSH-93 can be used as a library that can be embedded into an application to allow scripting.
Documentation for KSH-93 consists of an "Introduction to KSH-93", "Compatibility with the Bourne Shell" and a manual page and a README file. In addition, the "New KornShell Command and Programming Language" book is available from Prentice Hall.